Gas-impervious sheet material and method of making the same



April 21, 1931. w EER I 1,801,666

GAS IMPERVIOUS SHEET MATERIAL AND METHOD OF MAKING THE SAME Filed June 26, 1925 JUL/5777272? ZZZ/d am 5551?- Patented Apr. 21, 1931* wILIIIm o. GEER, or AKRON, 01:10, ASSIGNOR TO THE B. r. ooomucn oommiw, or

NEW YORK, Y., A CORPORATION OF N'EW'YORK' GAS-IMPERVIOUS SHEET MATERIAL ALlD METHOD MAKING THE SAME Application filed 111114226, 1925. Serial No. 89,703.

This invention relates to gas impervious sheet material, articularly adapted for containers of low' ensity gases such as are employed in the lighter-than-air type of air craft, and it has for an object to provide an inexpensive, light and durable material" which shall be less pervious with respect to the lighter gases, such as hydrogen and helium, than envelope materials heretofore 10 available.

In the past, it has been the common practice to employ in balloon construction a rubberized, close-woven fabric with an exterior coating of aluminum paint, which does not, hgwever, greatly increase the imperviousness 0 t for the dual purpose 'of imparting to the balloon a low visibility and of preserving the rubber of. the fabric from deterioration by the exclusion of light.

In the present invention, I provide a gasimpervious wall structure, suitable for the gas envelope of a balloon, consisting of a thin, flexible metal sheet or foil, which is highly impervious to gas diffusion, reenforoed with a covering of tough, strong sheet material firmly adhered to'one or both surfaces of the metal foil by any suitable bonding substance. The metal foil'is preferablymade of aluminum, or other metal or alloy capable of being formed into a tough, flexible, extremely thin sheet, and the reenforcing sheet is preferably a close-woven fabric, paper, rubber, or leather, and, where fabricor other absorbent fibrous sheet is used, it may be impregnated with a substance resistant to gas diffusion, similar to the rubberized balloon fabric now in commore use.

I have found that aluminum may be rolled into a. thin, tough sheet which not onlyis highly impervious to hydrogen, helium, and other light gases, but is also flexible to an unusual degree, and further on account of its resistance to corrosion and its light weight is particularly adapted for the wall structure of balloon envelopes. Tin foil, generally an alloy of tin and lead, is also well adapted for this purpose, and cere gas envelope, but is rather employed,

tain other alloys of copper, lead, bismuth,

ing fabric.

zinc, etc, are practicable and have the advantage of cheapness.

In order to secure most satisfactory re-' sults, the thin sheeted metal foil should be firmly and 'durably adhered to the reenforc- I have foundthat this may be accomplished by the use of suitable cements which are adhesive to rubber and to metals. Thus, cements having bases of rubber, gutta, balata and shellac may be employed. However, I fiud'that certain heat plastic rubber derivatives not only have a stronger adhesion for metals, and particularly for aluminum, but that they form a film which is highly impervious to gas difi'usion. Such substances may be prepared by reacting crude rubber, under the influence of heat, With various isomerizing agents, particularly sulfonic compounds having the general formula R-SO -X, wherein R represents an organic radical or a hydroxy group and X re resents a hydroxy group or chlorine.

Su stances of this character are described in my prior application, Serial No. 8,057,. filed January. 6, 1925, the following being especially practical and factory: (1) the tough, product of by weight, heated in a commercially satisnon-friable reaction p-phenol sulfonic acid, 7 parts and rubber, 100 parts, when I compact mass from 4 to 10 hours at 260290 F; or reaction products in which the phenol sulfonic acid is replaced by p-toluene sulfonyl chloride 9 parts, p-toluene sulfonic acid 7 parts, or other sulfonic acids and acid sulfonyl-chl orides approximately 7 to 9 parts, (2) a similar reaction product of 4 to 5 parts of concentrated sulfuric acid (sp. 'gr. 1.84) with a mixture of 100 parts of rubber and 2 to parts of pine tar, subjected to heat at 268 F. for 5 to 7 hours.

Of the accompanying drawings, Fig. l is a view in elevation of a balloon, broken away in part to show the wall structure of the gas envelope, and Figs. 2 and 3 are sec-- tions drawn to an enlarged scale of modified embodiments of my invention.

Referring to the drawings, I show in Fig. 1 a balloon 10 of the usual captive observation type having the wall structure 11 of the gas envelopemade up of a rubberized woven-fabric 12 to which is adhesively secured a metal foil 13, as by a bonding film 14, the foil being shown disposed interiorly of the envelope. The metal foil 13, however, may be employed at the outer side of the envelope, as indicated in Fig. 2.

In constructing the gas-impervious sheet material in accord with my invention, the metal foil 13 and the reenforcing sheet 12, as for example woven on one side with a suitable cement, and,

tions where it is after the solvent has evaporated, are pressed to ether to form a firm union of the two.

ere the heat-plastic substances of my prior application, Serial No. 8057, are employed, I may first apply a solution thereof to one side of the metal foil and bake in a dry heat. This gives a smooth, and flexible enamel surface of high imperviousness to gases. The enameled surface of the metal foil and the woven fabric may now be coated with a solution of the heat-plastic or with other suitable cement and joined by pressing together.

I find that where a rubberized balloon fabric is employed for reenforcing the metal foil, that a coating of a cement of the heatplastic upon the'aluminum and a coating of rubber cement on the fabric produce upon pressing the two together a very firm bond between the materials.

Alternatively, it is practicable in situadesirable to protect the metal foil of gas-impervious sheet material from damage due to impacts with other bodies to apply a reinforcing material to both sides of the metal so that the foil is embedded between reinforcing layers. Thus, P

I have shown in Fig. 3, a gas impervious wall structure consisting of a metal foil 15 having reinforcing sheets 16 of vulcanized rubber adhered to either side thereof by a suitable cement 17, 17 Sheet material of this character is impervious to a high de ree to the most penetrating gases and in a dition may be employed in the construction of gas-masks being particularly proof v against mustard gas.

Structures of the character hereinabove described may also be made with paper, leather and other flexible sheet materials as the'reenforcing member of the gas-im ervious sheet structure and it will be rea y understood that numerous other variations fabric, are each coated coating the sheet on one side with a tacky.-

rubber isomer, subjecting the sheet to a temperature sufficient to flow the coating material and to form, when cool, an enamel coatin on the aluminum sheet, and adhering a thm sheet of strong, flexible material to the coated surface of said metal sheet.

2. The method of making a gas-impervious sheetmaterial which comprises forminga thin tough flexible gas-impervious of a heat-plastic rubber isomer by coatin a metal foil on at least one side with a rub er isomer, and subjecting it to heat adequate to flux and bake the rubber isomer, and reenforcing the gas-impervious sheet thus formed by adhering a fabric thereto.

3. The method of making a gas-impervious sheet material which comprises forming a thin tough gas-impervious film of a heat plastic rubber isomer by coating a metal foil on at least one side with a rubber isomer and subjecting it to heat adequate to flux and bake the rubber isomer film. I

4. A gas-impervious sheet material comprising a film of a tough flexible heat-plastic rubber isomer protected on one side by a metal foil and reenforced on the other side by fibrous sheet material.

5. A gas-impervious sheet material comprising a film of a tough flexible heat-plastic rubber isomer baked on a metal foil.

6. A gas-impervious sheet material comprising a film of a tough flexible rubber isomer protected on one slde by a metal foil and reenforced on the other side by fibrous sheet material.

7. A gas-impervious sheet material comprising a baked film of a ton h flexible heatlastic rubber isomer hig y impermeable to gas diifusion.

- In witness whereof I have hereunto set my hand this 11th day of June, 1925.

WILLIAM C. GEER.

and modifications in the construction of the gas-impervious sheet material herein described may be made without departin from the principles of this =invention,-an

V I therefore do not wholly limit the claims to the s eific constructions herein set forth.

I c 1. The method of manufacturing a gasimpervious sheet material which comprises forming a thin, flexible sheet of aluminum,

use 

